This kind of heat exchanger includes a plurality of passages. A refrigerant is evenly distributed (or divided into streams) to the passages in order to improve the performance of heat transfer of the heat exchanger. A technique has recently been developed to arrange a plurality of heat exchange units, each including a plurality of fins and a plurality of flat tubes, in a row direction which serves as an air passing direction, in which air passes through the heat exchange units, in order to further increase the efficiency of heat exchange (see, Patent Literature 1, for example).
In Patent Literature 1, first ends of the flat tubes of a first heat exchange unit are in communication with first ends of the flat tubes of a second heat exchange unit through a row straddling header. An inlet header evenly divides the refrigerant into streams, which flow through the flat tubes of the first heat exchange unit. The streams temporarily merge into a stream of the refrigerant in the row straddling header, the refrigerant turns to the second heat exchange unit, the refrigerant is again divided into streams which flow through the flat tubes of the second heat exchange unit, the streams merge into a stream of the refrigerant in an outlet header, and the refrigerant flows out of the outlet header.